[aja1345]

Hi,

I am simulating a turbine with K-e-RNG turbulence model.

Used wall function is standard wall function.

I don't know about Y+ value on the wall(blade-hub-casing).

I am grateful that guide me about this value.

Thanks,

Best,

Aja

[nima_nz]

Y+ is a dimensionless value that show us the distance from the wall.
y+=(y*U*ro)/mu
'ro' is density of your fluid
U=(to/ro)^0.5
'to' is wall shear stress
'mu' is fluid viscosity
FLUENT gives you the Y+ on each wall. Usually, we want to achieve a proper Y+ for our model. you should check your wall treatment requirements in fluent user manual and then you should adjust your grid.
In this way for example if you want the Y+ be 1, you should solve your problem with an arbitrary near wall mesh and after that, give 'to' value on walls and find the y for Y+=1; then refine your mesh and solve again till achieve the desired mesh.

[jb pouillard]

HI,
If you want to use the standard wall treatment, you must compute your boundary layer for an y+ between 30 and 300 ...

[dale154]

Hi, I am wondering where in fluent you can see/find the computed value of y+ ?

Thanks,
Dale.

[jb pouillard]

Hi , you will find it , in the turbulence variables ... end of the list !!

[dale154]

Great, got it. Thanks!
Dale.